Semi-conductor chip manufacture requires the use of high purity chemicals and a distribution piping network. Many of the chemicals are hazardous and include volatile organic components. The piping network is subject to strict State and Federal requirements such as the Federal Clean Air Act of 1990. Every connection in the piping network poses a potential leak. While joints and connections in the piping can be welded or otherwise sealed as strongly as the pipe material itself, valves pose a particular area of vulnerability to leaks because of the moving parts contained in valves. In order to protect workers from leaks at the valves, valves for controlling and operating the piping network are contained in a multi-point of use chemical distribution box, known as a valve manifold box. Any number of pipes or lines can be connected to the box in the same manner as other joints in the line where the connection is at least as strong as the pipe or line material itself. The valves are the connected to the pipes and lines inside the valve manifold box The essential feature of the box is that it can be sealed so that in the event of leak the chemicals will be contained. However, the box must be capable of being opened for access to the valves and then closed again with a tight seal. The box must be capable of being opened and closed repeatedly with a tight and reliable seal each time. By sealing the area around the valves, even minor leakage of chemicals will accumulate in sufficient quantity to set of an alarm such as a fiber optic alarm inside the container. The use of a valve manifold box protects employees from exposure to the chemicals and also saves the company money in the event of a leak due to the high cost of these concentrated chemicals.
The valve manifold boxes in use today obtain a seal by using a box with a lid that is secured by a large number of thumbscews. The thumbscrews must be tightened initially by hand and then tightened down with a screwdriver thus requiring at least two manual operations per screw. In some cases the number of thumbscrews can be as high as one hundred or more requiring a large number of manual operations. The labor time involved in undoing such large number of thumbscrews for access and then replacing and seating the thumbscrews for re-sealing is significant. When power driven screw drivers are used to speed up the process the incidence of stripped screws goes up significantly, with a concomitant potential loss of seal effectiveness. Moreover, the monotonous and repetitious task tempts workers to skip thumbscrews or to properly seat only some thumbscrews thereby compromising the integrity of the seal. When access is needed in an emergency or in a very short time span for process control, the access time can be excessive. Therefore, a need exists for a valve manifold box that can be opened and closed quickly while ensuring a strong seal.
The prior art focuses on apparatus and methods for controlling the transfer and flow of chemicals from one container such as a holding container to another such as a process system container. However, the prior art does not address the problem of enclosing a valve manifold system within a sealed container where the valves can be accessed and re-sealed with relative ease. For example, U.S. Pat. No. 5,607,000 to Cripe et. al., discloses a non-venting hazardous material dispensing system which does not address the problem of protecting the control valves in the piping network. U.S. Pat. No. 4,601,409 to DiRegolo discloses a system for dispensing liquid chemicals such as photoresist including a valve to govern the flow from the containers. Once again, the disclosure is directed to solving problems in the flow and process control and does not address the problem of protecting valves in the piping network. Therefore, while valve manifold boxes in various forms are in use the semi-conductor manufacturing industry, there is a need for valve manifold boxes that solve the problem of providing a sealed environment around the valves and that are also capable of being opened and closed repeatedly while maintaining the quality and integrity of the seal.
Therefore, a need exists for a container that can be opened and closed easily and routinely with a minimum number of manual operations while ensuring a seal which will prevent the escape of any possible leaked chemicals.